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United States Patent | 5,120,171 |
Lasner | June 9, 1992 |
A bone screw having a helical thread that gradually increases in thickness from the tip to the head of the screw. The thin thread at the tip of the screw can be inserted into a bone with minimal tearing or cracking of the bone. The thicker treads ascending form the tip to the head of the screw displaces bone against the superior (top) thread surfaces. This displacement of bone increases the screw's resistance to being pulled-out of the bone. The thicker core just below the screw head increases the screw's ability to withstand compressive and distractive loads. The core is thickest just below the head because it is at that point on the screw that the fulcrum loads are greatest.
Inventors: | Lasner; Jeffrey (Purchase, NY) |
Assignee: | Stuart Surgical (Greensburg, PA) |
Appl. No.: | 618500 |
Filed: | November 27, 1990 |
Current U.S. Class: | 411/308; 411/310; 411/426; 606/73 |
Intern'l Class: | F16B 039/30 |
Field of Search: | 411/306,307,308,309,310,311,415,411,424,426,414,453 606/65,72,73,86 |
Re28111 | Jan., 1971 | Laverty. | |
D51291 | Sep., 1917 | Vorel. | |
D52511 | Jan., 1918 | Groh. | |
197933 | Dec., 1877 | Harvey. | |
1891895 | Dec., 1932 | Nagel | 411/453. |
1980093 | Nov., 1934 | Rosenberg. | |
2005672 | Jun., 1935 | Chaffee | 411/414. |
2570465 | Oct., 1951 | Lundholm | 128/92. |
2696817 | Dec., 1954 | Prevo | 128/92. |
2702543 | Feb., 1955 | Pugh et al. | 128/92. |
2772676 | Dec., 1956 | Pohl | 128/92. |
3109691 | Nov., 1963 | Burkhardt | 339/100. |
3233500 | Feb., 1966 | de Vellier. | |
3466748 | Sep., 1969 | Christensen | 606/73. |
3492906 | Feb., 1970 | Hauser | 411/415. |
3703843 | Nov., 1972 | Laverty. | |
3861269 | Jan., 1975 | Laverty. | |
4175555 | Nov., 1979 | Herbert | 411/415. |
4177524 | Dec., 1979 | Grell et al. | 3/1. |
4261351 | Apr., 1981 | Scherfel | 128/92. |
4463753 | Aug., 1984 | Gustilo | 128/92. |
4569338 | Feb., 1986 | Edwards | 606/73. |
4640271 | Feb., 1987 | Lower | 128/92. |
4756653 | Jul., 1988 | Berger | 411/426. |
4791918 | Dec., 1988 | Von Hasselbach | 128/924. |
4870957 | Oct., 1989 | Goble et al. | 128/92. |
Foreign Patent Documents | |||
77837 | Jun., 1918 | CH | 411/415. |
2033755 | May., 1980 | GB. | |
2090745 | Jul., 1982 | GB. |
"Youngstown Sliding Lag Screw and Plate" News Release dated Sep. 1, 1988. "Dr. Virgin Hip Fixation Screw", Surgical Equipment, vol. 7, No. 4, pp. 14 and 15, Jul., 1940. |